Blast furnace charging mechanism



Filed Oct. 15, 1935 4 Sheets-Sheet 1 MER W on m E 3 INVENTOR ATTORNEYOct. 19, 1937. F. I. SMITH BLAST FURNACE CHARGING MECHANISM Filed Oct.15, 1935 4 Sheets-Sheet 2 INVENTOR ATTORNEY BY (I 5 FIQZ 203 ZbZ m) m wml. FL E E 8 M8 mL E TL T AA AR TM T 5 L R R Oct. 19, 1937. sMlTH2,096,567

BLAST FURNACE CHARGING mzcnmusm Filed Oct. 15.1935 4 Sheets-Sheet 3 TD|31 T0 REVOLVING TOP CONTROLLER INVENTOR ATTORNEY Oct. 19, 1937. l. SMITHBLAST FURNACE CHARGING MECHANISM Filed Oct. 15, 1955 4 She ets-Sheet 4 m7 n M M 3 1%! I. INVENTOR ATTORNEY certain average height.

Patented Oct. 19, 1937- BLAST FURNACE CHARGING MECHANISM Frank 1. Smith,Wilkinsburg, Pa.., minor to i I Otis Elevator Company, New York, N. Y.,-I corporation of New Jersey Application 0ctober 1 5, 1935, Serial No.45,031 scam (Cl. 214-36) The invention relates to the control of thecharging of blast furnaces.

In a typical blast furnace installation, the stock for the furnace isloaded into a skip bucket at a loading point. The skip is then hoistedto the top of the furnace where the stock is dumped onto a small bell.The small bell is then operated to dump the stock onto a-large bell andthen reclosed. Another load is then brought up from the loading pointand dumped onto the small bell which thereupon dumps the stock onto thelarge bell and recloses. This cycle of operation is repeated until acertain number of loads have beendumped onto the large bell whereupon,after reclosure of the small bell, the large be dumps the charge intothe furnace.

It is desirable to maintain thelevel of the stock in the furnace, thatis the stock line, at a vention is to automatically control the heightof the stock in the furnace.

It may happen that, as the time arrives for dumping the large bell, thestock line is such, due for example to the furnace not being drawn orthe charge becoming stuck, that to dump the large bell would overfillthe furnace. This would be highly. objectionable, not only from thestandpoint of operation, but it might prevent all the new stock droppinginto the furnace and thus prevent the closing of the large bell.

It is a specific object of .the present invention to automaticallycontrol the charging of a blast furnace in accordance with the stockline so that the furnace will not be overfilled.

One feature of the invention is to stop operation of the chargingmechanism when, as the time arrives to dump the large bell, the stockline of the furnace is above a certain point.

Another feature resides in automatically resuming operation of thecharging mechanism when the stock line drops to a certain point.

Other features and advantages of the invention will become apparent fromthe following description and appended claims.

In the drawings:'-

Figure 1 is a simplified schematic representation of a blast furnaceinstallation embodying the invention;

Figure 2 is a view of stock line recorder mechanism employed in theinstallation;

Figure 3 is a diagrammatic representation of commutating mechanismassociated with the bell operating mechanism;

Figure 4 is a simplified wiring diagram of certain of the power andcontrol circuits of the con- The object of the in- 'trol system for theblast loading pit 20l furnace chargin anism; and i g mach Figure 5 is adiagrammatic representation of a control panel, showing particularly therelationshipof the coils and contacts oi. the various electromagneticswitches employed in the control system of Figure 4.

For a general understanding of the invention reference may be hadtoFigure 1, wherein va-. rious parts of a blast furnace installation areindicated by reference-characters. The stock for the furnace is carriedin a skip bucket 200 from a to a hopper 202 at the top of the furnace.Two

skips are illustrated, these skips running on separate tracks from theloading pit to the hopper. Each of the tracks is arranged at the top toautomatically dump the skip as it arrives at the hopper.

The skip buckets are raised and lowered by skip hoisting mechanism. Thismechanism comprises roping 205 connected to one of theskips and passingaround a drum 200 which is driven by a motor I90, and similar ropingconnected to the other skip and passing around drum 208. The roping isarranged on the drum so that one skip is raised from the loading pit tothe hopper as the other is returned to the pit. One end of the ropingfor one skip is connected to the skip and extends therefrom upwardly toan idler sheave 208 and thence downwardly around hoisting drum 206. Theroping for the other skip is simihoisting motor.

larly arranged but is wound oppositely on. the drum. Anelectromechanical brake 2 having a release coil I16 is provided forstopping the The hoisting motor and brake are controlled through amaster control switch I69 arranged at the loading platform for manualoperationby an operator. Mechanically operated switching dumped onto thesmall bell, the cycle of operation is repeated, dumping the load ontothelarge bell. When a specified number of loads have been dumped onto thelarge bell, the large bell is opened, dumping the charge into thefurnace.

When the small bell is opened and dumps a ceiving another load. Also,the large bell is not mechanism. Small bell load, it is returned toclosed position before resmall bell has been closed, and the large bellis returned to closed position before the small bell is opened. Thisseals the furnace, an outlet for the gases at the top of the furnacebeing provided by pipe 2|6, which carries the hot gases to the heatersand other parts in the installation.

The bells are operated by the bell hoisting opened until the low rod 220to one end of lever 22I. At its opposite end lever 22! carries acounterweight 223 of sufilcient mass to counterbalance the weight of thebell and the rod plus the weight of the load of material resting on thebell, and to provide sufficient force to maintain a sealing pressurebetween the bell and its seat. Large hell 2 l 5 is connected to a lever225 by a rod 224 which extends through hollow rod 220. v with acounterweight 226 which counterbalances the weight of the bell and rodas well as the weight of material resting on the bell and pro videssufficient sealing pressure between the bell and its seat.

In the hoisting machine for the bells, drums 221 and 228 are looselymounted upon a shaft 230 supported by bearing pedestals mounted on base23l. Hoisting cable 232 for small bell, 2l4 hasits lower end secured todrum 221, passes over sta-.

tionary pulleys 233 and 234 and is connected to the weighted'end oflever 22!. Hoisting cable 235 for large bell 215 has its lower endsecured to drum 228, passesover stationary pulleys 236 and 231 and isconnected to the weighted end of lever 225. Rotation of drum 221 fromthe neutral position shown causes cable 232 to move the weighted end oflever 22l upwardly, thereby opening small bell 2, and rotation of drum228 from this neutral position causes cable 235 to move the weighted endof lever 225-upwardly, thereby opening large bell A driving gear 240 iskeyed to shaft 230. A lug 241 is provided on each side of the gear. Alug 242 is arranged on drum 221 in the path of movement of the lug onthe left sideof gear 240 so as to be engaged thereby when the gear isrotated to move from neutral in a counterclockwise direc tion as viewedfrom the left hand end of the bell hoisting machine. Continued movementof the gear after the engagement of the lugs causes drum 221 to rotatetherewith, thereby opening the small bell. To close the small bell, thedirection of rotation of gear. 240 is reversed to allow drum 221 toreturn to neutral under the influence of weight 223. A similar lug 243is arranged on drum 228 in the path of movement of the other lug 24l soas to be engaged thereby when gear 246 is rotated from neutral in theopposite direction. Continued rotative movement of the gear after lug243 is engaged causes rotation of drum 228 to open large bell 2 l5. Inclosing hell 2 l 5, the direction of rotation of gear 246 is reversed toallow drum 228 to return to neutral under the influence of weight 226.

Driving gear 240 is driven through a train of gears 245 by motor I50mounted on base 23!. An electromechanical brake 246 having a releasecoil I43 is provided for bringing the rotating members rapidly to restwhen the motor is deenergized: The operation of the motor and brake iscontrolled by switching mechanism 250 actuated in accordance with thepositions of the bells, by certain of the switches actuated inaccordance with the positions of the skips and by switching 2 isconnectedby hol- Lever 225 is likewise providedmechanisi'n actuated bythe'stock line recorder mechanism, these various switching mechanismsacting .through the intermediary of electromagnet-1c switches. Switchingmechanism 250 is illustrated as driven from shaft '23fl. 7

Commutating mechanism H0 is also driven from shaft 230, this mechanismacting'to control the operation of the bell indicator 252 and to controlthe sequence of operation of the bells. The bell indicator comprises acolumn of lamps J09 arranged at the loading platform for observation bythe operator to indicate which of the bells. is in operation and, in thecase of the small bell, the number of times it has been operated sincethe opening of the large bell.

Referring to Figure 3, commutating mechanism H0 comprises a series ofstationary contacts H2 and H4-l22 inclusive arranged in the arc of -acircle and a contact segment I I3 for engaging and bridging thesestationary contacts. This segment is arrangedon a shaft 255 for rotationtherewith. The segment is biased into position against a stop 256 withsegment H3 in engagement with stationary contact I I2 by a weight 251.This weight is connected to a pulley 258 on shaft 255. The segment ismoved clockwise against the force of its biasing weight by means of aratchet 260 and to shaft 255 while the ratchet is connected by a rod 262to a'. link 263. This link in turn is actuated by a crank motion fromshaft 230 as diagrammatically illustrated. With shaft 230 in neutralposition, the crank arm extends horizontally from the center of theshaft.

Upon clockwise rotation of the shaft to open the small bell, the motionimparted to link 263 lifts rod 262. This causes the ratchet to engagethe ratchet wheel and move the wheel an amount sufficient to rotatesegment H3 into engagement.

with the next stationary contact. From the position in which the segmentis shown, the first step of movement causes segment H3 to engagestationary contact H4 and to disengage stationary contact H2. As thesmall bell is returned to closed position, pawl 264 cooperates with the.

. operation of the large bell. Upon counterclockwise rotation of shaft230 from neutral to open the large bell, the ratchet is moved away fromthe ratchet wheel by the crank action and a collar 265 on rod 262engages and releases pawl 264, permitting weight 251 to return thesegment to the position shown against stop 256. This resets thecommutating mechanism for another cycle of operation. The ratchet 260does not engage the ratchet wheel upon return of shaft 230 to neutral toclose the large bell. After the closing of the large bell, the smallbell is again operated, starting another cycle of operation;

The stock line recorder comprises a rod 210 extending downwardly intothe furnace at the top thereof. At the bottom end this rod isprovidedwith a plate 21! for resting on the stock. The stock line recordermechanism acts to permit the rod to follow the stock, the upper end ofthe rod being suspended by a rope 212 which passes over idler pulley213, downwardly over idler ratchet wheel 26l. The ratchet wheel issecured I pulley 214, around a tensioning sheave 215, and thenceupwardly and around a drum 216. The drum 218 is driven by the motor 61which is provided with an electromechanical brake 218 having a releasecoil 64.- Commutating mechanism 58 is driven by motor 61 in accordancewith the movement of rod 210. This mechanism controls a stock lineindicator 218. This indlcator.comprises a series of lamps 62 arranged ina vertical column at the loading platform for observation by theoperator.

Reference may be had to Figure 2, which illustrates a stock linerecorder machine. Idler pulley 214 is rotatably mounted 'on an arm 280supported on a pedestal 28l on base 282. Tensioning sheave 215 isrotatably mounted on a shaft 283 carried by an elongated frame 284. Thistensioning frame 284 is guided for vertical movement within anotherframe 285. Frame 284- is biased for downward movement by its own weighuand the weight of sheave 215. For a portion of this downward movementthis force is augmented by that of a spring 286 arranged between a plate292 and a spring seat 281 secured by oppositely disposed studs 288 toframe 285. Additional oppositely disposed studs 290 depend from frame285 and each is provided at its lower end with a nut 29I for cooperatingwith plate 292 to form a stop forlimiting the expansion of the spring. Anut 293 on each of studs 288 serves to adjust the compression of thespring.

Frame 284 carries cams 294. and 295. Cam 294 is for operating limitswitch 21 while cam 295 is for operating limit switch 22, these limitswitches being mounted on frame 285. ,Theseswitches act throughelectromagnetic switching mechanism to control the operation of motor 61and brake 218.

Frame 285 is provided with arms 296 having bearing lugs 291 formed onthe ends thereof. A pivot shaft 300 extends through apertures providedin these lugs from the base to the top of pedestal 28L This arrangementpermits the bracket to swing as rope 212 is wound on drum 216 or unwoundtherefrom.

Motor 61 for driving drum 216 is vertically mounted. On the lower end ofits shaft the motor is provided with a worm 30! which acts through wormwheel 302 to drive the drum shaft 303. The drum shaft acts through atrain of gears 304 to drive all-operating shaft 305 for commutatingmechanism 58. This commutating mechanism comprises a plurality ofstationary contacts 36-54 inclusive arranged in a circle. The first ofthese contacts 36 is somewhat elongated. A contact ring isarranged in acircle concentric with that of the stationary contacts and a bridge 60,comprising a pair of electrically connected brushes, acts to bridge thecontact ring with individual stationary contacts. This bridge isarranged on an arm 306 mounted on shaft 305 for rotation thereby. On theother end of arm 306 is a stop 301 which cooperates with a staticnary'lug 308 to bring the bridge to rest upon clockwise rotative movementwith the brushes bridging the contact ring and stationary contact 36.

In operation, assume that the rod 210 has been lifted against a stop3I0. With the rod in this position, frame 284 is held against the forceof spring 286 in position where cam 294 opens switch 21. Uponenergization of motor 61 to pay out rope 212, the tensioning frame islowered before movement of rod 210 takes place. cause the weight ofsheave 215 and frame 284 plus the force exerted by spring 286 is morethan twice the weight of rod 210. As the tensioning switch 22.

is beframe moves downwardly, spring 286 expands and a position isreached where plate292 engages nuts 28l on studs 280, thereby relievingrod 210 from the effect of the force of'spring 286. The weight of frame284 and sheave 215 is less than twice the weight of rod 210 so that asthe rope continues to be paid out the rod is lowered into the furnace.When plate -21I. engages the top of the stock in the furnace, the rodcomes to a stop and further paying out .of rope 212 permits thetensioning frame 284 to continue its downward movement until cam 295engages and opens This causes motor' 61 to be deenergized and the brakeapplied to bring the mechanism to a stop.

This mechanism permits the rod to continue to follow the stock,preferably at intervals as will be explained later. When the timearrives to open the large bell, motor 61 is energized to .take up onrope 2.12. This results first in raising the tensioning frame'until apoint is reached where the top of the frame engages plate 292 where theforce of spring 286 is added to the weight of the tensioning frame andsheave. This increases the downward force exerted on rope 212 at sheave215 sufficiently to cause rod 210 to be lifted until it is brought torest by engagement with stop 3I0. Thereaftenthe tensioning frame israised against the force of spring 286 until cam 294 opens switch 21,which effects the deenergization. of motor 81 and the application of thebrake to bring the mechanism to a stop.

The invention is applicable to installations provided with a revolvingtop. A revolving top has been illustrated in Figure 1. It comprises ahopper 3l5 for the small bell, arranged for rotation in steps by a motor3I6 through gearing 311. A swivel connection 3|8 between hollow rod 220and lever 22l is provided to permit rotative movement of the small bell.The purpose of the revolving top is to effect a certain disposition ofthe various materials of the stock within the furnace. Y

When the stock in the furnace is within a certain distance of the largebell, the furnace is considered full. This distance varies from six toeight feet in present day installations, depend- ,ing upon the area ofthe furnace at the stock line. The invention involves controlling theoperation of the charging mechanism so that no new stock is admitted tothe furnace-when the furnace is full as'the time arrives for dumping thelarge bell. As soon as the stock in the furnace settles to a point wherethe furnace is no longer considered full, the large bell is dumped andthe operation of the charging mechanism is resumed.

In carrying out the invention, the stock line recorder is utilized tocontrol the operation of the large bell. If, as the time arrives to openthe large bell, the line of the stock in the furnace is such that therod is at or above a certain point in the furnace, the operation of thelarge bell is prevented. In the preferred arrangement, another load maybe dumped upon the small bell but, unless in the meantime the rod hasbeen permitted to drop below this point, further operation of the bells,the skip hoist and also of the revolving top, if provided, is prevented.When the stock line in the furnace falls below the predetermined point,the stock line recorder mechanism acts automatically to raise rod 210 upagainst the stop and to cause the opening of the large bell. Uponreclosing of'the large bell, the

small bell is dumped and the charging mecha bodying the invention, Thecontrol and power' circuits of the various units are illustrated ascombined in a single wiring diagram Not all of the circuits are shown,the circuits being simplified for convenience of description. However,enough of the circuits for the various units are shown to attain anunderstanding of the principles of the invention.

No attempt is made in Figure 4 to show the coils and contacts of thevarious electromagnetic switches and devices in their associatedpositions, a straight wiring diagram being employed. The separation ofthe coils and contacts ,of the switches enables the circuits to bearranged in an across the line form, rendering them comparativelysimple.

The numerals employed in designating the various elements of the wiringdiagram are arranged in sequence, the lowest number, in this case II,appearing in the upper left hand corner and the succeeding numbersfollowing in numerical sequence from left to right downwardly. on thesheet of drawings. The arrangement of numerals in this sequencefacilitates location of any element referred to in the description.

The electromagnetic switches have been designatedas follows:

AS-Auxiliary sequence switch BA-Bell accelerating switch BS-Bellsequence switch CL-Charge limiting switch HBHoist bell interlock switchgg} noist direction switches HS-Hoist speed switch LBLarge bell switchOSLarge bell operating switch RAR0d accelerating switch RI-Ie-Rodhoisting switch RI-IRRod hoisting relay R1r-R0d lowering switch SB-Smallbell switch TRTime relay Throughout the description which follows, theseletters, in addition to reference numerals, will be applied to parts ofthe above designated switches. For example, contacts RLI2 indicate thatthese contacts are on the rod lowering switch, while operatingc'oilRHRI03 indicates that the coil operates the rod hoisting relay. Therelationship of the coils andcontacts of the above switches may be seenfrom Figure 5, where the switches arearranged in alphabetical order. Itis to be understood that the exact arrangement of the switches isdetermined by the requirements of the particular installation.

The switches of the switching mechanisms of the various units will betermed limit switches. In accordance with the type of wiring diagramemployed, the individual limit switches of each unit are shownseparated. In order to difierentiate between the limitswitches of thevarious units, those operated by the skip hoist mechanism are designatedgenerallyby the letter S, those operated by the bell operating mechanismare designated generally by the letter B and those operated by the stockline recorder mechanism are designated generally by the letter R.

Commutating mechanism III], in addition to cuits to a series of jacksI24 to I32 inclusive.

controlling the bell indicator, controls the cir- A plug I31 is providedfor insertion in any one of the jacks to control the number of smallbell operations. The jacks are arranged on the control panel shown inFigure 5.

The blast furnace control units are illustrated as arranged for directcurrent power supply. The power supply lines are designated LI and L2. II and I6 are blades of a double pole knife switch for connecting thesystem to the power supply. It will be ass closed.

The motor GTof the stock line recorder mechanism has its armaturedesignated 13, series field winding 69 and its separately excited fieldwinding 65. A series resistance 10 and by-pass resistance 14 areillustrated for controlling the current flowing in armature 13 of themotor. motor I of the bell operating mechanism has its armaturedesignated I55, series field winding I46 and-its shunt field windingI40. A series resistance I41 and by-pass resistance I49 are illustratedfor controlling the current flowing in armature I of the motor. Themotor I90 of the skip hoist mechanism has its armature designated I83,series field winding I80 and its separately excited'field winding I89. Aseries resistance I8I and by-pass I81 are illustrated for controllingthe current fiowing in armature I83 of the motor.

Master control switch I69 comprises a bridging contact segment I63operated in one direction to bridge contacts I51 and in the otherdirection to bridge contacts I68. Contacts I51 control the circuit forcoil HUI58 of one hoist direction switch while contacts I68 control thecircuit for coil HDI10 of the other hoist direction switch. These coilsare also subject to limit switches.

The skip limit switches may be regarded as arranged in sets, each ofthose functioning for one of the skips, which will be termed skip a,having the letter a appended to its designation and each of thosefunctioning for the other skip, which will be'termed skip 1), having theletter b appended to its designation. The limit switches of set a areS3211, SI59a and SIIiGa, while those of set b are SBIb, SI1Ib and SI14b. Additional limit switches SI92 and SIQIb may be provided forcontrolling the revolving top which will be referred to later. The belllimit switches are designated B84, B85, B92, B94, B98 and BI01, whilethose of the stock line recorder mechanism are designated R22 and R21.

It will be assumed that skip b is in the pit below the loading platformand that skip a is in dumping position at the top of the furnace. Undersuch conditions limit switches S8 lb, SI1Ib and Sl14b are closed andlimit switches 882a, SI59a and SI66a are open. Switch SI59a being openprevents the energization of coil HUI58 of hoist direction switch HU.However, as limit switch SI1lb is closed, the hoisting ofskip "b uri'iedthat this switch has been This circuit may be traced from supply lineLI,

to bypass contacts R'I'RI64 and HSI6I. It also engages. contacts HDI86and HDI'I8 to complete a circuit for the armaturel83 of the skip hoistmotonwhich is from lin'e LI, through contacts -HDI 86, armature I83,contacts HDII8, series field winding I 80 and-resistance I8I to line L2.Con.- tactsHDII5 are also engaged, completing a circuit for release coilII6 of the skip hoist electromechanical brake.-

'* The brake-being released and the skip hoist motor being energized,its separately excited field win'ding I89 being directly connectedacross lines LI and L2, the skip operating mechanism starts in adirection to hoist skip b and to return skip a to the loading pit. Asthe counter E. M. F. of armature I83 builds. up, coil HSI84 of the hoistspeed switch is energized sufiiciently to engage its contacts HSI85 andseparate its contacts HSI82 and I-ISISI. Contacts HSIGI are in theinitial energizing circuit for the coils of the direc-.

tion switches, these contacts serving to prevent the sudden reversal ofthe direction of rotation of the skip operating motor. These contactsare now by-passed by contacts HDI'I3,.m.aintaining coil HDIIIlenergized. Contacts HSI82 discon nect by-pass resistance I8'I fromacross armature I83, while contacts HSI85 short-circuit resistance I8Iand series field winding I80. This brings the skip hoist motor up tofull speed.

As skip 1) leaves the pit, limit switch SI59a closes and thereafterlimit switch SI'I4b opens. It will be assumed that contacts HBI62 of thehoist bell interlock switch are engaged before the opening of limitswitch SII4b takes place. This being the case, the circuit for coilHDIIU is maintained through contacts HJBI62 and HDI'I3.

As skip b nears its dumping position, limit switch SI66a closes and ash;reaches this position limit switch SI'IIb opens. The opening of 'limitswitch SI'IIb breaks the circuit for coil HDI'IO which separates itscontacts HDIBG and HDI I8 to disconnect the skip hoist motor from thesupply lines and also separates its contacts HDI'I5 to deenergize brakerelease coil "6 of the skip hoist electromechanical. brake. Thebrake isapplied to bring the skip hoisting mechanism to a stopwith skip b in itsdumping position and skip "(1 in its loading position, being assisted bythe by-pass resistance I81 reconnected across the motor armature by thedropping out of hoist speed switch HS to engage contacts HSI82. It willbe understood that the control system may be arranged to cause theby-pass resistance to. be con-' nected across the armature'before thefinal stopping operation and that resistance I 8| may be controlled inseveral steps to control acceleration HUI'I'I and HUI.88 to establish acircuit for the skip hoist motor for rotation in the opposite-direction. At the same time it engages contacts HUI6'I to energizebrake release coil I'IB. Thus skip a is started in the up direction andskip b is started on its return to the loading station.

As skip a reaches its dumping position, it is dumped. 1 ."Skip' b isstarted virrthe updirection by m'ovement of control switch jsegment I63in a position to bridge contacts I68, as previously described. Nofurther description'of raising and lowering the'skips is necessary,asitfis Simply a .repetitio'nof that alreadyjdescribed; 5''

Both bells are closed while a skip is being dumped With the bellsclosed, bell limit switches B84, B85'and B94 are open and bell limitswitches B92, B98 and BIO'I are closed. Skip limit -switch--S82a isopened as skip a arrives within about ten' feet of its dumping position.Similarly limit switch S8Ib is opened as skip b arrives within about tenfeet of its dumping position. Thus either limit switch S8Ib or limitswitch S8211 is open when the skip is being dumped.

Assume that skip a is being dumped. As the skip is returned to theloading pit and reaches a point say ten feet away from the dumpingposition, limit switch S82a closes. Thus, as limit switch S8Ib isalready closed, this completes a circuit for operating coil SE90 of thesmall bell switch. This circuit is from line LI through skip limitswitches S8Ib and S82a, contacts H386 of the hoist bell interlock'switchand contacts AS8I of the auxiliary sequence switch, coil SE90, interlockcontacts LB9I of the large bell switch, bell limit switch B92 andcontactsTR93 of the time relay to line L2, operating coil TRI38 of thetime relay being energized at this time, through contacts SBI35 of thesmall bell switch and contacts LBI36 of the large bell switch Small bellswitch SB, upon operation, separates contacts SB!" and SBI35 and engagescontacts SBI4I, SBI44 and SBI56. Contacts SE91 are interlock contacts inthe circuit for coil LB96 of the large bell switch. Contacts SBI35 breakthe circuit for coil TRI38 of the time relay which separates itscontacts TR93, the circuit for coil SE90 being thereafter maintainedthrough resistance I04. Contacts SBI44 and SBI5B complete a circuit forarmature I55 of the bell operating motor through resistance I41.Contacts SBI4I complete a circuit'for release coil'l43 of the belloperating mechanism electromechanical brake.

The brake being released and the bell operating motor being energized,its separately excited field winding I40 being connected directly acrosslines LI and L2, the bell operating mechanism starts in operation, thedirection of'rotation of the motor being such asto' permit the openingof the small bell. its operating coil'BAI52 connected across armatureI55. This switch operates upon the counter E. M. F. of the motorreaching a certain value to separate contacts BAI48 and engage contactsBAI53. The separation of contacts BA I48 disconnects by-pass resistanceI49 from across armature I55 while the engagement of contacts BAI 53short-circuits series resistance I41 and series field winding I46. Thisbrings the bell operating motorup to full speed.

As the bell operating mechanism starts in op-' eration in a directionfor lowering the small bell, its limit switches B85 and B94 close. Limitswitch B85 establishes a circuit by-passing skip limit switches S8Ib and882a and contacts HB86 and ASB'I in the circuit for coil SE90. Thepurpose of limit switch B94 will be explained later. After the closingof limit switch B85, limit switch B84 closes, which completes a circuitfor op- Bell accelerating .switch BA has a brought to astop by theopening tr, limit switch -SI59d. Skip b, which has been returned to itsloading position, is loaded as" skip.a is being crating coil H883 of thehoist bell interlock switch through skip limit switches S8") and 3920.This switch, I upon operation, separates contacts H389 and engagescontacts H890 and HBIH.

Contacts H300 establish a self-holding circuit bellswitch, this switchbeing maintained energized, however, through bell limit switch B85.

As'the small bell is lowered it dumps the stock thereon onto the largebell. As it reaches its full lowered position, belllimit switch B92opens, breaking the circuit for coil SE90 oi the small bell switch. Thesmall bell switch, upon dropping out, reengages contacts SB9I andSBI35and separates contacts SBI4I, SBI44 and SBI56. .The separation ofcontacts SBI4I deenergizes brake release coil I43 while the separationof contacts SBI4'4 and SBISG disconnects bell operating motor armature Iand series field winding I46 from lines LI and L2. The hoisting motorbeing deenergized and the brake: being applied, the bell operatingmechanism is brought to a stop, the brake being aided by by-passresistance I49 which is reconnected across motor armature I55 by thereengagement of contacts BAI48 as the armature voltage drops to acertain value. It is to be understood that the control system may bearranged to cause the by-pass to be reconnected across the motorarmature before the final stopping operation and that resistance I41 andseries field winding I46 may be controlled in steps to controlacceleration and retardation of the bell operating motor.

The reengagement .of contacts SE91 completes a circuit for operatingcoil LB96 of the large bell switch from line LI through bell limitswitch B94 and the coil L396, contacts SB9I, bell limit switch B98 andresistance I04 to line L2. Owing to resistance I04, the voltage appliedto boil LB96 is insufficient to cause the large bell switch to operate.However, the reengagement of contacts SBI35 completes a circuit iiorcoil TRI38 of the time relay which, upon expiration of its timeinterval, engages contacts TR93 to short-circuit resistance I04. Uponthe shortcircuiting of resistance I04, suflicient voltage is applied tocoil LB96 to operate. the large bell switch for returning the small bellto closed position. Thus the small bell is maintained open for asuflicient time to insure that all the stock thereon is dumped.

The large bell switch, upon operation, separates contacts LB9I. andLBI36 and engages contacts LBI42, LBI45 and LBI54. Contacts LB9I serveas an electrical interlock for coil SE of the small bell switch.Contacts LBI36 break the circuit for coil 'I'RI38 of the time relay.Contacts LBI45 and LBI54 establish a circuit for armature I55 of thebell operating motor for reverse rotative movement. The engagement ofcontacts LBI42 completes a circuit for brake release coil I43. Thus thebell operating mechanism electromechanical brake being released and itsmotor being energized, the bell operating mechanism operates in thereverse direction permitting the biasing weight for the small bell toreturn the smallbell to closed position.

As the small bell reaches closed position, bell limit switch B94 opens,breaking the circuit for coil L396 of the large bell switch. The largebell switch, upon dropping out, reengages contacts LBOI and LBI" andseparatescontacts LBI42,

LBI45 and LBI54. Contacts LB9I prepare a circuit for another operationof small bell switch SB 'andco-ntacts LBI30 reestablish a circuit forcoil 'I'Rlfl'ot the time relay. Contacts LBI54 and LBI45 break thecircuit for the bell operating motor. Contacts LB I42 break the circuitfor brake release coil I43. Thus, the bell operating motor beingdeenergized and the brake being applied, the bell operating mechanism isbrought to a stop.

The above described operation of the bell operating mechanism isrepeated for the next load dumped onto the small bell by a skip. Underthe assumed conditions of operation, skip "b" is the next to dump itsload. Thus, skip limit switch S8: is opened as the skip nears itsdumping position. The opening of this switch breaks the circuit for coilH383 of the hoist bell interlock switch which drops out to reengage itscontacts H1396 and to separate contacts H890 and HBI62. The reengagementof contacts H386 further prepares the circuit .for reenergization ofcoil S390 of the small bell switch. Upon operation of the skip operatingmechanism to return skip b to the skip loading position and after sayten feet of downward movement of the skip, skip limit switch- S8Ibcloses completing the circuit for coil SE90 of the small bell switch.Thus the cycle of operation of opening the small bell to dump the stockonto the large bell and returning the small bell to closed position asabove described is repeated.

These operations are repeated until a predeterthe small bell onto thelarge bell. The number of loads is selected by inserting plug I31 in acorresponding one of the jacks. Assume that it is desired to have fiveloads dumped onto the large bell before the above cycle of operationsisinterrupted. For this operation, plug I31 is inserted in the fifthjack I28.

As previously explained, each successive operation of the small bellcauses an operation of the bell commutating mechanism III). Upon thedumping of the first load onto the large bell, segment II3 of thecommutator device moves off stationary contact H2 and into engagementwith stationary contact II4. This causes lamp I09 connected to contactII2 to go out and the lamp connected to contact II4 to be illuminated.This indicates that the mechanism is on the first small bell operation.Upon the second small'bell operation, segment II3 moves into engagementwith contact H5, lighting lamp I09 connected to that contact. In thisway the successive lamps are lighted indicating the number of operationsof the small bell.

Upon the fifth operation, segment II3 moves into engagement withstationary contact II8, not only lighting the lamp connected thereto butalso completing a circuit through jack I28 and plug I31 for coil BSI34of the bell sequence switch. This switch, upon operation, engagescontacts BS'I08. completing a circuit for coil ASIDE of the auxiliarysequence switch. Switch AS operates to separate contacts A881 and toengage contacts ASI00 and ASI05. 'Contacts ASI05 establish aself-holding circuitf Contacts AS8l are interlock contacts and serve toprevent the energization of coil SE90 of the small bell switchduringthis portion of the cycle of operation. Assuming charge limiting switchCL to be deenergized, the engagement of contacts ASI00 completes acircuit for coil RHRI03 of the rod hoisting rela through contacts CLIOI.I

The rod hoisting relay, as will be explained later, causes the rod ofthe stock line recorder to be raised from the stock line in the furnaceuntil it is brought to a stop by abutment 3!!! (see Figure l), aspreviously described. As the rod is lifted, bridging contact 60 of thestock line recorder commutating device 58 is moved back into positionwhere'it bridges contact 36 with segment 35. This completes a circuitfor coil OSBI of the large bell operating switch. This switch separatescontacts OS'H and engages contacts Si02. The purpose of contacts OSIIwill be explained later. Contacts 0Sl02 complete a circuit throughcontacts ASIODand CLIOI by-passing bell limit switch B94 in the circuitfor coil L336 0! the large bell switch. Inasmuch as switch BS isenergized during the opening of the small bell, this by-pass circuit isestablished at the .time the small bell is reclosed and switch B34opens. Thus the large bell switch is maintained operated. This maintainsthe brake released and the motor energized, continuing the rotation ofthe bell operating mechanism past neutral position and effecting theopening or the large bell to dump the stock accumulated thereon into thefurnace.

As the large bell starts to open, limit switches B85 and B94 close andas the bell reaches iull open position, limit switches B98 and Bill!open. The opening of switch Bill-i breaks the circuit for coil AS I 06of the auxiliary sequence switch, which drops out to reengage contactsA881 and to separate contacts ASIUO and ASIOS. The reeng'agement ofcontacts LBS! of the large bell switch completes a' circuit for coil$390 of the small bell switch through bell limit switches B35 and B32and resistance I04. The reengagement 01 contacts LBI36 reestablishes acircuit for coil TRI38 of the time relay which, upon expiration of ittime interval. engages contacts TR33 to short-circuit resistance I04,causing the small bell switch to operate. This switch effects therelease of the brake and establishes circuits for the bell operatingmotor to eflect the return of the large bell to closed position. As thelarge bell reaches closed position, bell limit switch B35 opens,deenergizing the small bell switch. This causes the bell operatingmechanism to be brought to a stop.

During the-operation of the large bell, segment H3 of the bellcommutating device is returned to the starting position where it engagescontact I I2 to reestablish a circuit for the lamp I03 connected to thiscontact. This indicates that a large bell operation is beingperformedand the next operation will be an operation of the small bell.This cycle of operation as above described is repeated upon the dumpingof another skip load onto the small bell and the return of the skiptoward the loading pit, the large bell being dumped again after theselected number of loads have been dumped thereon from the small bell.

Coil RHRIII3 of the rod hoisting relay is maintained energized after theseparation of contacts ASIUD, as a result of the opening of bell limitswitch Biol as the large bell reaches fully open condition, through belllimit switch B94 and contacts OSI02. Thus this relay is maintainedenergized until switch B34 opens as the large bell reaches closedposition. When this occurs, relay RHR drops out to .reengage contactsRHRII and RHR32 and to separate contacts RHRM. 'Contacts RHRN are in thecircuit for coil EH25 of the rod hoisting switch, preventing theestablishment of a circuit for this coil, while contacts RHRII are inthe circuit for coil RLIB oi' the rod lowering switch. Operating coilRLIB or the rod lowering switch is further controlled by means of atiming device, designated generally by referonce letters TD. A timingdevice suitable for this purpose is illustrated in Figure 5.

Referring to Figure 5, this timing device comprises a motor 3 whichvoperates through reduction gearing "2 to drive a shaft 3l3.

An idler gear 3 is supported by one arm of a bell crank lever 320 freelymounted on shaft 3. The idler gear is driven by the reduction gearingand is adapted to be thrown into mesh with another gear 32i bylever'320. The other arm or lever 320 constitutes the armature of aclutch magnet, the coil of which is designated I3. 'When this magnet isenergized, lever,320 is swung counterclockwise to mesh idler gear 3 withgear 32l. When motor 3 is in operation and the ciutch magnet isenergized, meshing gear 3 with gear 32l, gear 32l is rotated in aclockwise direction. Upon the engagement of a pin 322 on gear 32| witharm 323 01' bell crank lever 324, lever 324 is swung graduallycounterclockwise about its pivot. This lever is connected by a spring325 to a contact lever 323. When'the lower end of the spring is movedbeyond the center line through the pivot for contact lever 328, thecontact lever is thrown clockwise about its pivot with a snap action.This disengages a contact carried by the lever from a cooperatingstationary contact and moves another contact carried bythe lever intoengagement with another stationary contact. These cooperating contactsare designated l5 and 23. Upon the separation of contacts l5 the timingmotor is deenergizedas will be shown later. Ii! the clutch magnet ismaintained energized the contacts will be retained in this position withcontacts I! separated and contacts 23 in engagement. Upon deenergizationof the clutch magnet, lever 320 drops, disengaging idler gear 3 fromgear 32l and a torsion spring 321 associated with gear 32| returns thegear in a counterclockwise direction to the position from which itstarted. As this movement takes place, pin 322 moves away from lever324, which is swung back about its pivot by a spring 330. As spring 32!passes the center line through the pivot for contact lever 326, thecontact lever is snapped back into the position illustrated, separatingcontacts 23 and reengaging contacts l5. As gear 32! arrives at itsformer position, it is brought to rest by the engagement of a pin 33lcarried thereby with a stop 332. The time interval provided by thetiming device is from the time the motor and clutch are energized untilthe engagement oil contacts 23 takes place. This time interval may valfor which the timing device is set expires before the large bell isclosed, contacts TD23,

upon engagement, are maintained so for the separation of contacts TDIB,although breaking the circuit for armature TD and field winding TD20 ofthe timing device motor. does not deenergize clutch magnet coil TDI3.Under such conditions, the engagement of contacts RHRII completes thecircuit for coil RLI3 of the rod lowering switch. Otherwise, thiscircuit is completed upon the engagement of contacts TD23 of the timingdevice as the time interval expires. This circuit is through contactsRHRIT, coil RLI8, contacts RHZI, stock line recorder limit switch R22and contacts TD23.

Switch RL, upon operation, separates contacts RLI2 and RL26 and engagescontacts RL30, RL59, RL66 and RLI8. Contacts RL26 are arranged in thecircuit for coil RH of the rod hoisting switch. These contacts serve asan electrical interlock. Contacts RL30 by-pass-contacts TD23 of thetiming device, thereby establlshing a self-holding circuit. ContactsRLI2 break the circuit for the timing device motor armature TDM andfield winding 'I'D20 and for clutch magnet coil 'I'Di3. This causes theseparation of contacts TD23 and the reengagement of contacts TDl5.Contacts RL66 and RL'I8 complete a circuit for armature 13 and seriesfield winding 69 of the stock line recorder motor through resistance 10.The engagement of contacts RL59 completes a circuit for brake releasecoil 64 of the stock line recorder mechanism. The separately excitedfield winding 65 of the recorder motor is connected across lines LI andL2. Thus, upon the brake being released, the stock line recordermechanism starts in operation, the direction of rotation of the motorbeingsuch as to lower the rod into the furnace. The initial operation ofthe stock line recorder effects the reengagement of limit switch R21.When plate 292 engages nuts 29! (Figure 2), the rod starts to lower intothe furnace.

The lowering of the rod takes place at a slow speed owing to the factthat contacts RL66 prevent the energization of coil RAH of the rodaccelerating switch and contacts RAIS remain separated. Thus, seriesfield Winding 69 and resistance" remain connected in series with themotor armature I3 and the by-pass resistance 14 remains connected acrossthe motor armature.

When the rod has been lowered into position where the plate on the lowerend thereof strikes the stock in the furnace, the recorder mechanismacts as previously described to open limit switch R22. This breaks thecircuit .for coil RLI8 'of the rod lowering switch. Switch RL drops outto reengage contacts RLI2 and RL26 to separate contacts RL30, RL59, RL66and RLI8. Contacts RL26 are in the circuit for coil EH25 of the rodhoisting switch, the circuit for this coil being open at contacts RHR24.The separation of contacts RL66 and RLI8 breaks the circuit for theoperating motor of the recorder mechanism andas contacts RL59 break thecircuit for the brake release coil 64, the stock line recorder mechanismis brought to a stop with the rod in its lowered position.

During the lowering of the rod, bridging contact 60 of commutator device58 moves into position successively bridging the stationary contactswith feed contact 35. Upon the disengagement of contact 60 fromstationary contact 36, the circuit for coil OS6I of the large belloperating switch is broken. This switch thereupon drops out to separatecontacts OS|02 in the circuit for causing operation of large bell switchLB to effect the opening of the large bell and reengages contacts OS" inthe circuit for coil RA'I2 of the rod ac-- celerating switch. Uponthe/engagement of contact 60 with stationary contact 31 a circuit iscompleted through contacts RHR32 of the rod hoisting relay for operatingcoil CL33 of the charge limiting switch. Switch CL, upon operation,separates contacts CLIOI in the circuit for coils LB96 and RHRID3 andengages contacts CL3I to establish a self-holding circuit. Upon theengagement of contact 60 with contact 38, a circuit is completed for thefirst of the series of lamps 62 of the stock line indicator.

The reengagement of contacts RLIZ reestablishes the circuit for thetiming device which starts in operation. Upon the expiration of the timeinterval for which this device is set, say one minute, it reen'gagescontacts TD23 to reestablish the circuit for coil RLI8 of the rodlowering switch. This switch operates as before to permit the plate onthe lower end of the rod to drop to the point to which the charge in thefurnace has settled. The above cycle of operation is repeated at thespecified time intervals.

Assume that before bell sequence switch BS is operated bridging contact60 is moved into engagement with contact 43. This establishes ashort-circuit forv coil CL33 of the charge limiting switch, causing thecharge limiting switch to drop out to reengage contacts CLI 0 I. Thus,upon the operation of auxiliary sequence switch AS to engage contactsAS160, as a result of the operation of bell sequence switch BS to engagecontacts BSIOB, a circuit is established for coil RHRI03 of the rodhoisting relay. This relay operates as previously described to separatecontacts RHRH and RHR32 and to engage contacts RHR24. Contacts RHR24establish a circuit for coil EH25 of the rod hoisting switch throughcontacts RL26 and limit switch R21. Contacts RHRI'I prevent theenergization of coil RLI8 of the rod lowering switch. The rod hoistingswitch, upon operation, separates contacts RH2I and engages contactsRH63, RH68 and RH'I6. Contacts RHZI are in the circuit for coil RLI8 andserve as an electrical interlock. Contacts RHBB and RH'I6 complete acircuit for armature I3 and series field winding 69 of the stock linerecorder operating motor through series resistance 10 in a direction foroperating the motor to lift the rod, the brake being released as aresult of the engagement of contacts RH63 to establish a circuit forbrake release coil 64. Inasmuch as the circuit for coil RHRI03 isestablished during the opening of the small bell, the hoisting of therod startsduring this portion of the cycle of operation. In addition,coil RA'I2 of the rod accelerating switch is energized during thehoisting of the rod. This causes contacts RAT! to be separated,disconnecting by-pass resistance 14 from across armature I3 and contactsRA'I5 to be engaged, shortcircuiting resistance 10 and series fieldwinding 69. Thus the rod is lifted at full speed so as not to delay theopening of the large bell upon return of the small bell to closedposition.

The bridging contact 60 is returned to its former position as the rod israised in the furnace. Upon the engagement of this contact withstationary contacts 31, a circuit is not completed for coil CL33, owingto the fact that contacts RHR32 are separated. The engagement ofbridging contact 60 with contact 36, however, establishes a circuit forcoil OS6I of the large bell operating switch which operates, aspreviously described, to engage contacts 0SI02 in a circuit for causingthe opening of the large bell and to separate contacts OS". Theseparation of contacts OS'H breaks the circuit for coil RA'I2 of the rodaccelerating switch which separates contacts RA'IS and engages contactsRA". The separation of contacts RAIS reinserts resistance 10 and seriesfield winding 69 in series with motor armature thereafter brought to astop by stop IIO and thereafter the motor is brought to a stop by theopening of limit switch R21 to deenergize .coil EH of the rod hoistingrelay.-

So long as the stock in the furnace has settled to or below a pointcausing the dropping out of charge limiting switch CL as the timearrives for opening the large bell, the above described cycle ofoperation will be continued. However, if the stock line is above suchpointat this time, the

mechanism operates automatically to prevent the opening of the largebell until the stock has settled to or below this point.

Assume that at the time that bell sequence switch BS is energized inpreparation for effecting the opening of the large bell, the stock linein the furnace is at such a height as to prevent bridging contact 60 ofcommutating device 58 engaging contact 43 to drop out charge limitingswitch CL. Under such conditions, the operation of auxiliary sequenceswitch AS to engage contacts' ASIilildoes not establish a circuit forcoil RHRl03'of the rod hoisting relay, owing to the fact that contactsCLIM are separated. Thus, the hoisting of the rod of the stock linerecorder does not take place. However, the operation of the belloperating mechanism to effect the dumping of the stock from the smallbell separated. Thus, not only is the opening of the large bellprevented when the furnace is full but also further operation of thesmall bell is prevented aiter it completes the dumping of the last loadof stock onto the large bell.

Since further operation of the bell operatin mechanism is prevented whenthe furnace is full as the time arrives to dump the large bell, belllimit switch B84 is not closed and coil HBO! of the hoist bell interlockswitch is not energized. Thus, contacts HBIBI remain separated, whichbrings the skip operating mechanism to a stop. For an understanding ofthis operation, assume that skip a is the one which dumped the last loadonto the small bell. Thus, uponthe re, closure of skip limit switch 882aas skip 0'' starts down the incline, a circuit is not established forcoil H1383 owing to hell limit switch B84 being open. Contacts H'BIB?therefore remain separated so that the opening of skip limit switchSl'Hb, which occurs after the closing of limit switch 582a, breaks thecircuit for coil HDIIO of hoist direction switch HD (switch HID beingthe hoist direction switch which was op-' erated under the assumedconditions). This causes the skip operating mechanismv to be brought toa stop with the skips in the positions to which they have-been moved.Thus the entire charging operation is suspended. The stock linerecorder, however, continues to function, permitting the lowering of therod at successive intervals to follow the stock in the furnace.

When the stock in the furnace settles to a point permitting theoperation of commutating device 58 to effect the bridging of contact 4 3and contact 8l,- coil CL of the charge limiting switch isshort-circuited, causing the reengagement of contacts CLIOI. This causesthe operation of the rod hoisting relay RHR to cause the hoisting of therod. As the rod reaches its uppermost position, switch OS is operated toengage contacts OSIM, establishing a circuit for coil LB" oi the largebell switch. This causes,

the bell operating mechanism to open the large bell, dumping thematerial thereon into the furnace. As the large bell reaches openposition, bell limit switch Bill! opens to deenergize coil ASIOB of theauxiliary sequence switch, which engages contacts 'ASB'I. Thus, acircuit is established by-passing bell limit switch B85, therebycontinuing operation of the bell operating mechanism through neutral toopen the small bell as the large bell is returned to closed position. Asthe small bell opens, bell limit switch B closes after reclosure of belllimit switch B85. The closing of switch B84 operates hoist bellinterlock switch HEB, which engages contacts HE"! and, the operatormaintaining the master control switch in operated condition, this startsthe skip hoisting mechanism in operation from the point at which it wasbrought to a stop. Thus, as soon as the stock line in the furnace fallsto a point where the furnace is no longer considered full, the chargingmechanism is automatically restarted in operation from the point it lefton.

The lamps 82 of the stock'line indicator indicate the height of thestock in the furnace. The first of the lamps shows when the furnace isfull while those connected to contacts beyond contact 43 show that thefurnace is not full and to what point below the full line the stock hassettled.

It has previously been pointed out that the invention is applicable to ablast furnace installation having a revolving top. Circuits forinterlocking the revolving top controller with the other controlmechanism have been illustrated in Figure '4. The revolving topcontroller may be of the type shown in the patent to Mortensen, No.1,790,942, dated February 3, 1931, and the circuits have beenillustrated for application to such type of control. Skip limit switchesSI9ib and Bilia act to control the operation of the revolving top, theselimit switches corresponding to limitswitches i3 and ll of the revolving'top control system shown in the Mortensen patent. With thisarrangement, when the furnace is full as the time arrives for openingthe large bell, skip limit switches Slfllb and SI92a prevent furtheroperation of the revolving top controller. Skip limit switch Si92a isclosed as skip 11" reaches its dumping position, while skip limit switchSlfllb is closed as skip b reaches its dumping postion. At other timesthese limit switches are open. Thus, as the skip hoist mechanismis-brought to a stop upon a certain distance of skip travel after a loadis dumped on the small bell under conditions where operation of thelarge bell is prevented because the furnace is full. the operation ofthe revolving top is also prevented. Contacts RTRIS are contacts on arevolving top relay, the operating coil of which may be connected inparallel with coil lllw of the control system of the Mortensen patent.With this arrangement, contacts R'I'Ri remain separated until the cycleof operation of the revolving top has been completed and the revolvingtop motor has been brought to a stop. This prevents the starting of theskip hoist during revolving top operation, which in turn preventsoperation of the bell operating mechanism.

Thus it is seen that, when the furnace is full as the time arrives todump the large bell, not only is further operation of the bellsprevented and the skip hoist brought to a stop, but. in an installationprovided with a revolving top, further operation of the revolving top isprevented. It will also be seen that as soon as the stock line in thefurnace drops to a point where the furnace is no longer considered full,the operation of the charging mechanism is automatically resumed.

As many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:-

1. In combination; a blast furnace having a small bell and a large bellat the top thereof, the large bell being arranged below the small bell;mechanism for operating said bells; control means for. causing said belloperating mechanism to operate the small bell a predetermined number of'times to one operation of the large bell; a rod extending downwardlyinto; the furnace at the top thereof; hoisting mechanism for said rod;means for controlling the operation of said rod hoisting mechanism tocause the bottom of the rod to follow the stock as it sinks in thefurnace between operations of the large bell; means operable upon thelast of the said predetermined number of operations of the small bell,under conditions where the top of the stock in the furnace beneath therod is below a certain level, to cause operation of said rod hoistingmechanism to lift the rod, said means being ineffective to causeoperation of said rod hoisting mechanism to lift the rod when the top ofthe stock beneath the rod is above said predetermined level; and meanscontrolled by the lifting of said rod and operable as the rod in beinglifted reaches a predetermined height in the furnace to cause operationof said bell operating mechanism to operate the large bell.

2. In combination; a blast furnace having a small bell and a large bellat the top thereof, the large bell being arranged below the small bellto receive stock from the small bell; mechanism for dumping successiveloads of stock onto the small bell; mechanism for operating said bells;means for causing said bell operating mechanism to open the small bellto dump stock therefrom onto the large bell and thereupon to close thesmall bell; means for causing said bell operating mechanism to open thelarge bell after a predetermined number of operations of the small belland to reclose the large bell after the stock has been dumped therefrominto the furnace; a rod extending downwardly into the furnace at the topthereof; hoisting mechanism for said rod; means for controlling theoperation of said rod hoisting mechanism to cause the bottom of the rodto follow the stock in the furnace during said predetermined number ofoperations of the small bell, said means being responsive to the last ofsaid predetermined number of operations of the small bell to cause saidrod hoisting mechanism to lift the rod; means actuated in accordancewith the position of said rod operable, when the top of the stock in thefurnace beneath the rod as the time arrives to lift the rod is above acertain point, to prevent operation of said rod hoisting mechanism tolift the rod and to prevent further operation of said bell operatingmechaism upon the return of the small bell to closed position after saidlast of said predetermined number of operations thereof; and meansresponsive to the stopping of said bell operating mechanism to stopoperation of said mechanis for dumping stock onto the small bell.

3. In combination; a blast furnace having a small bell and a large bellat the top thereof, the large bell being arranged below 'the small bellto receive stock from the small bell; mechanism for operating saidbells; means for causing said bell operating mechanism to open the smallbell to dump stock therefrom onto the large bell and to reclose thesmall bell; means for causing said bell operating mechanism to open thelarge bell after a predetermined number of operations of the small bellto dump stock thereon and to reclose the large bell after the stock hasbeen dumped therefrom into the furnace; a rod extending downwardly intothe furnaceat the top thereof hoisting mechanism for said rod; means forcontrolling the operation of said rod hoisting mechanism to cause therod to follow the stock in the furnace between operations of the largebell, said means being responsive to the last of said predeterminednumber of operations of the small bell to cause said rod hoistingmechanism to lift the rod; and means actuated in accordance with theposition of said rod operable, when the bottom of the rod is at or abovea predetermined point in the furnace, to prevent operation of said rodhoisting mechanism to lift the rod and to prevent operation of said belloperating mechanism as the time arrives for operating the large bell toopen the large bell and also the small bell upon its return to closedposition after said last of said predetermined number of operations ofthe small bell, said last named means thereafter acting upon the bottomof the rod dropping below said predetermined point to cause said rodhoisting mechanism to operate the large bell and to large bell beingarranged below the small-bell to receive stock from the small bell;mechanism for dumping successive loads of stock onto the small bell;mechanism for operating said bells; means for causing said belloperating mechanism to open the small bell after a load has been dumpedthereon and to reclose the small bell after the stock has been dumpedtherefrom onto the large bell; means for causing said bell operatingmechanism to open the large bell after a predetermined number of loadshave been dumped thereon by the small bell and to reclose the largebell'after the stock accumulated thereon has been dumped into thefurnace; a rod extending downwardly into the furnace at the-top thereof;hoisting mechanism for said rod; means for controlling the operation ofsaid rod hoisting mechanism to cause the rod to follow the stock in thefurnace and to lift the rod prior to the opening of the large bell; andmeans actuated in accordance with the position of said rod forcontrolling the operation of said rod hoisting mechanism, said balloperating mechanism and said mechanism for dumping stock onto the smallbell, said last named means acting, when the bottom of the rod is at orabove a predetermined point in the furnace as the time arrives foroperating the large bell, to prevent operation of said rod hoistingmechanism to lift the rod, to prevent operation of said bell operatingmechanism to dump either bell and to stop operation of said mechanismfor dumping stock onto the small bell, said last named means thereafteracting upon the bottom of the rod dropping below said predeterminedpoint to cause said rod hoisting mechanism to lift the rod, to

cause said bell operating mechanism to dump the large bell and to resumedumping of the small bell after the large bell is returned to closedposition and to cause said mechanism for dumping stock onto said smallbell to resume operation.

5. In combination; a blast furnace having a small bell and a large bellat the top thereof, the large bell being arranged below the small bellto receive stock from the small bell; mechanism for dumping successiveloads of stock onto the small bell; mechanism for operating said bells;means for causing said bell operating mechanism to open the small bellafter a load has beendumped thereon and to reclose the small bell afterthe stock has been dumped therefrom onto the large bell; means forcausing said bell operating mechanism to open the large bell after apredetermined number of loads have been dumped there on by the smallbell and to reclose the large bell after the stock accumulated thereonhas been dumped into the furnace; a rod extending downwardly into the.furnace at the top thereof hoisting mechanism for said rod; means forconoperation of said bell operating mechanism as the time arrives foroperating the large bell to open the large bell and also the small bellupon its return to closed position after dumping said last of saidpredetermined number of loads onto the large bell and to stop operationof said mechanism for dumping stock onto the small bell after dumpinganother load onto the small bell after the small bell has dumped saidlast load onto the large bell, said last named means thereafter actingupon the bottom of the rod dropping below said predetermined point tocause said rod hoistin mechanism to lift the rod, to cause said belloperating mechanism to dump the large bell and to resume dumping of thesmall bell after the large bell is returned to closed position and tocausesaid mechanism for dumping stock onto said small bell to resumeoperation.

FRANK 1.3mm.

